This invention relates to a roller cage for a longitudinal guiding device, mounted on rolling bearings, with substantially continuous apertures made therein in which rollers are inserted for longitudinal leading of a guiding part in a guided part, in particular of guide pillars in bores of punching dies, tools for mold making or in general machine construction.
Roller cages of this type are known. Usually with roller cages of this kind the apertures for receiving the rollers are obtained by punching. Afterwards the rollers are inserted into the corresponding holes, after which the material of the roller cage is plastically deformed in the region of the inner and outer edge by pressing so that a protruding edge is formed, whereby the rollers are held in the apertures.
Owing to the punching out step for producing the apertures, the side faces, which border the apertures, have a certain roughness. The rollers are guided by these side faces. This means that the rollers come into contact with these side faces when the leading part is moved with respect to the led part. Because of the surface roughness of the side faces, the rollers are thus subjected to an abrasive wear and tear, on the rolling face as well as on the front faces. This reduces the life of the rollers, and thus the life of the longitudinal guiding device.
Putting the apertures in the roller cages by punching and plugging the inner and outer edge areas of the apertures after insertion of the rollers requires several operational steps. Inaccuracies can thereby occur, which can have as a consequence an imprecise placement of the roller. This leads to the roller not rolling exactly on the surfaces to be borne, whereby here, too, the abrasion is greater, which once again has an effect upon the life of longitudinal guiding devices of this kind. Through imprecise placement of the rollers in the apertures, the pressure of the roller surfaces on the side faces of the apertures also increases, which once again results in a faster attrition of the roller.
The object of the present invention is therefore to design the apertures in the roller cage such that a more precise placement of the rollers inserted therein is achieved, whereby the attrition of the rollers and of the roller cage is reduced, and the life of correspondingly equipped longitudinal guiding devices is increased.
This object is achieved according to the invention through a roller cage for a longitudinal guiding device, mounted on rolling bearings, with substantially continuous apertures made therein in which rollers are inserted, wherein the apertures, which are machined down, have a substantially rectangular cross-section, formed by four side faces, and each side face forms an inside edge region and an outside edge region, and the inside edge region of each aperture has collar-shaped projections which protrude out of the side faces and which extend at least over part of the circumference of the aperture, and the outside edge region of the aperture is plastically deformed through pressing in along at least one part of two side faces which run parallel to the longitudinal axis of the roller such that a protruding edge is formed over the surface of the two side faces of the aperture.
The four corner regions of the aperture formed by the four side faces are preferably each provided with a recess, which could be designed semi-cylindrical, for example. Achieved thereby is that this region of the aperture cannot come into contact with the roller inserted in the aperture, whereby wear and tear on the roller can be reduced, in particular when it is provided with two cambered rolling surfaces, which are provided on the two end regions of the roller.
When using the above-mentioned rollers, it is preferable if the protruding edge running outside along the two sides is limited laterally in each case by the two recesses. Also avoided thereby is that this edge comes into contact with the bearing region of the respective roller, whereby abrasion is reduced. This applies also to the collar-shaped projections, which are provided along the two sides running parallel to the longitudinal axis of the roller, and which are also limited laterally by the recess provided in each corner region.
When rollers having a cambered surface are inserted into the apertures of the roller cage, it is preferable to dispose the collar-shaped projections in the region of the recesses, whereby their front edges run substantially in diagonal direction over the corner area. Achieved thereby is that the bearing region of this roller does not come into contact with the collar-shaped projections, whereby abrasion is reduced and the life thereby increased.
A further, additional advantage results if in the middle region of the two sides running parallel to the longitudinal axis of the roller a further recess is provided in the respective side faces in each case. Thereby prevented is contact between the bearing face of the roller and these two side faces. Achieved in addition is that the protruding region also has a respective recess.
The apertures in the roller cage are preferably designed such that they can be rough-drilled and obtained by milling in a one operational step, it being necessary to use just one milling tool. Putting the apertures in the roller cage is thereby simplified, which has a positive effect upon the precision and the economic efficiency.